Sear mechanism for guns



March 6, 1934. F. K. HOWARD SEAR MECHANISM FOR GUNS Filed Aug. 14, 1933 2 Sheets-Sheet 1 Inventur Fnlfrest K Hmward @WW/M March 6, 1934. F. K. HOWARD SEAR MECHANISM FOR GUNS Filed Aug. 14, 1933 2 Sheets-Sheet 2 Inventur Y MM ,M ma m Attorney Patented Mar. 6, 1934 STATE OFFICE 2 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government; for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a sear mechanism for guns and is an improvement on the mechanism shown in copending application of Richard C. Coupland Serial No. 627,244 filed August 2, 1932.

In the application a vertically movable sear carried by the bolt of the gun and adapted to be elevated by the firing pin on forward movement thereof is provided with laterally projecting lugs selectively engageable between lugs on a transversely movable sear whereby the sear is held immovable.

'I'he improvements of this invention are directed to the means for releasably locking the sear, the purpose being to provide a simpler and stronger construction.

To these and other ends, the invention consists in the construction, arrangement and combination of elements described hereinafter and pointed out in the claims forming a part of this specication.

A practical embodiment of the invention is illustrated in the accompanying drawings, wherein:

Fig. 1 is a longitudinal sectional view of the rear end of the bolt showing the position of the parts with the firing pin in cocked position.

Fig. 2 is a similar view showing the position of the parts with the firing pin in fired position.

Figs. 3 and 4 are views in rear elevation of the bolt corresponding respectively to Figs. l and 2.

Fig. 5 is a plan view of the bolt of Fig. 1.

Fig. 6 is a detail view in rear elevation of the sear, parts being shown in section.

Fig. 'l is a detail View in side elevation of the sear; parts being shown in section.

Fig. 8 is plan view of the sear.

Figs. 9, 10 and 11 are views respectively in plan, side and rear elevation of the transverse slide.

Fig. 12 is a view showing the vertically movable slide in rear and side elevation.

Fig. 13 is a sectional view on the line 13-13 of Fig. 10.

Referring to the drawings by numerals of reference there is shown a bolt 5 adapted to be reciprocally mounted in the receiver frame of a machine gun. Within the bolt is a longitudinally disposed firing pin 6 normally urged in a forward direction by means of a spring 7 housed in the ring pin and seated on a vertical pin 8 passing through the bolt. 'I'he firing pin is cocked in a well known manner by the lever 9 when the bolt moves in recoil.

The firing pin is held in cocked position by means of a sear 10 which is mounted for vertical sliding movement in a slot 11 in the rear end of the e0 bolt and is formed with ribs 12 on its opposite sides which nt in grooves 13 in the side walls of the slot. The sear includes a transversely disposed lug 14 movable into and out of a transversely disposed groove 15 formed in the upper sure5 face of the firing pin adjacent to its rear end. The rear face 16 of the lug 14 is inclined to coact with a correspondingly inclined face 17 dening the rear wall of the groove 15 in the firing pn- On the front end of the sear is a bent finger 18, the extremity of which is disposed in the groove 15 of the firing pin when the latter is in the cocked position as shown in Fig. l. In Fig. 2 where the firing pin is in the red position the extremity of the ringer rests on top of the rear end of the riring pin and serves to hold the sear in the elevated position. A lug 19 is provided on the inner side of the nger 18 for a purpose that will appear later.

A plunger 20 mounted in the upper portion of 80 the Sear and urged outwardly by a spring 21 is seated against a bar 22 rigidly carried by the pin 8. The plunger opposes elevation of the sear and normally tends to depress it into engagement with the firing pin. The lower portion of the sear is formed with an opening 23 to permit rearward movement of the firing pin.

The rear end of the bolt is formed with a transversely disposed slot 24 having grooves 25-25 at its inner end. A slide 26 (Figs. 9 to 1l) insertable 90 in the grooves 25 from either side of the bolt is disposed in front of the sear. A more or less centrally located aperture 28 in the slide permits passage of the rear end of the ring pin.

On one end of the slide and projecting rearwardly therefrom is a housing 29 carrying a plunger 3i) adapted to engage the side of the sear.

A lug 31 on the other end of the slide is adapted to engage the opposite side of the sear and limits movement of the slide under the action of the plunger. The lug 31 is provided with cam faces 32-32 adapted to be engaged by cam faces 33-33 (Fig. 12) on a vertically movable slide 34 which is arranged to be elevated by the hand trigger mechanism oi' the gun. The cam faces are du- 105 plicated to provide for operation when the slide is in reversed position.

Referring to Figs. 9 to 11 the upper and lower portions of the slide 26 are each formed with a projecting rail 35 disposed in the plane of the 110 lug 19 on the inner side of the finger 18 yof the sear when the sear and the slide are assembled in the bolt. Each rail is provided centrally with a slot or recess 36 which is slightly wider than the lug 19 and Vinto which the lug is permitted to move .when the recess is in alignment therewith as seen in Fig. 2. In the normal locking position (Figs. 1 and 3) the under side of the rail 35 engages the upper side of the lug 19 andprevents the sear from being raised through the camming action exerted by the firing pin. When the kslide is moved laterally (to the left in Fig. fi) the re'- cess 36 is in position to receive the lug 19.

When the sear 10 has been released, the firing pin spring 7 moves the ring pin 6 forward, the.

transverse lug 14 on the sear being cammed out oi the groove 15 of the firing pin. The firing pin Vcomes to rest withY its rear end directly under-Y neath the finger 18 so that the sear is held in thev of the bolt through aconventional trigger motor or it is actuated indirectly through the vertical slide34. Y

Y-I claim. i

1. In a gun, a reciprocable breech boit, a firing pin movable relative to the bolt and having va groove with'a cam face in its rear end, a iiring pin spring, a cooking lever carried by the bolt and adapted to retract the ring pin, a vertically movable sear carried by the bolt, means for normally depressing the sear, a lug on the sear disposed inthe groove o the firing pin when the sear is de- -vation of thesear, and means for normally mainspring, a cooking lever carried by the boltvand pressed and having'fa cam face engageable with the cam face of the ring pin, a projecting finger on the sear positionable in the groove of the ring pin and engageable bythe rear end of the firing pin when in iiring position whereby the sear is held in the elevated position, a lug on the inner side of the fingeryatransversely'movable slide reversibly mounted in the bolt in front of the Sear and having an aperture through which the firing pin is movable, the upperand lower portions of the slide each having a projecting rail adapted to ride on the lug of the nger and hold the sear in depressed position, each rail having a recess adapted to receive the lug on the finger upon eletaining the slide in Sear-holding position.

2. In a gun, a reciprocable breech bolt, a ring pin movable relative to the bolt and having a groove with a cam vface in its rear end, a firing pin adapted to retract thering pin, a vertically mov- Y ablesear carried by the bolt, means for normally.

Ving an aperture through which the Vfiring pin Yis movable, said slide having a projecting rail adapted to ride on the lug of the finger and hold the y1-u sear in Vdepressed position, said rail having a recess adapted to receive the lug on the finger upon elevation of thesearyand means for normallyv maintaining the slide in Sear-holding position.'V

v VlOltREiSTI' K. HOWARD.Vv Y 

